import { useEffect, useState } from "react";
import { api, ApiError } from "../api";
import type { AdminStats } from "../types";
import { BarChart3, Package, CheckCircle2, Tag, FolderTree, Inbox } from "lucide-react";

const STATUS_LABEL: Record<string, string> = {
  active: "在用",
  merged: "已合并",
  deprecated: "已停用",
};

function Card({
  icon,
  label,
  value,
  hint,
}: {
  icon: React.ReactNode;
  label: string;
  value: string | number;
  hint?: string;
}) {
  return (
    <div className="rounded-lg border bg-white p-5">
      <div className="flex items-center gap-2 text-sm text-gray-500">
        {icon}
        {label}
      </div>
      <div className="mt-2 text-2xl font-semibold text-gray-800">{value}</div>
      {hint && <div className="mt-1 text-xs text-gray-400">{hint}</div>}
    </div>
  );
}

export default function StatsPage() {
  const [stats, setStats] = useState<AdminStats | null>(null);
  const [error, setError] = useState("");

  useEffect(() => {
    api
      .stats()
      .then(setStats)
      .catch((e) => setError(e instanceof ApiError ? e.message : "加载失败"));
  }, []);

  return (
    <div className="mx-auto max-w-5xl">
      <h2 className="mb-4 flex items-center gap-2 text-lg font-semibold text-gray-800">
        <BarChart3 className="h-5 w-5 text-emerald-600" /> 数据概览
      </h2>

      {error && (
        <div className="mb-3 rounded bg-red-50 px-4 py-2 text-sm text-red-700">{error}</div>
      )}

      {!stats ? (
        <div className="text-sm text-gray-400">加载中…</div>
      ) : (
        <>
          <div className="grid grid-cols-2 gap-4 md:grid-cols-3">
            <Card
              icon={<Package className="h-4 w-4" />}
              label="商品总数"
              value={stats.products.toLocaleString()}
            />
            <Card
              icon={<CheckCircle2 className="h-4 w-4 text-emerald-600" />}
              label="合格档案"
              value={stats.qualified.toLocaleString()}
              hint={`质量分 ≥ ${stats.min_score} 且在用`}
            />
            <Card
              icon={<BarChart3 className="h-4 w-4" />}
              label="平均质量分"
              value={Math.round(stats.avg_quality * 100)}
              hint="满分 100"
            />
            <Card
              icon={<Tag className="h-4 w-4" />}
              label="品牌数"
              value={stats.brands.toLocaleString()}
            />
            <Card
              icon={<FolderTree className="h-4 w-4" />}
              label="分类数"
              value={stats.categories.toLocaleString()}
            />
            <Card
              icon={<Inbox className="h-4 w-4" />}
              label="待审核投稿"
              value={stats.pending_submissions.toLocaleString()}
            />
          </div>

          <div className="mt-6 rounded-lg border bg-white p-5">
            <h3 className="mb-3 text-sm font-medium text-gray-700">按状态分布</h3>
            <div className="space-y-2">
              {Object.keys(stats.by_status).length === 0 ? (
                <div className="text-sm text-gray-400">暂无数据</div>
              ) : (
                Object.entries(stats.by_status).map(([st, n]) => {
                  const pct = stats.products > 0 ? (n / stats.products) * 100 : 0;
                  return (
                    <div key={st} className="flex items-center gap-3 text-sm">
                      <span className="w-16 text-gray-600">
                        {STATUS_LABEL[st] || st}
                      </span>
                      <div className="h-3 flex-1 overflow-hidden rounded bg-gray-100">
                        <div
                          className="h-full bg-emerald-500"
                          style={{ width: `${pct}%` }}
                        />
                      </div>
                      <span className="w-12 text-right text-gray-500">{n}</span>
                    </div>
                  );
                })
              )}
            </div>
          </div>
        </>
      )}
    </div>
  );
}